Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$69.52	9.554%	$76.1619	$76.16	$76.15	$76.20
Purchase #2	$140.74	10.413%	$155.3953	$155.40	$155.40	$155.40
Purchase #3	$142.92	6.809%	$152.6514	$152.65	$152.65	$152.70
Purchase #4	$180.46	8.691%	$196.1438	$196.14	$196.15	$196.10
Purchase #5	$209.43	9.152%	$228.597	$228.60	$228.60	$228.60
Purchase #6	$156.38	4.287%	$163.084	$163.08	$163.10	$163.10
Purchase #7	$151.73	13.538%	$172.2712	$172.27	$172.25	$172.30
7 purchase totals =	$1,051.18		$1,144.3046	$1,144.30	$1,144.30	$1,144.40