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	$172.69	12.336%	$193.993	$193.99	$194.00	$194.00
Purchase #2	$124.32	4.627%	$130.0723	$130.07	$130.05	$130.10
Purchase #3	$156.32	3.132%	$161.2159	$161.22	$161.20	$161.20
Purchase #4	$123.33	11.658%	$137.7078	$137.71	$137.70	$137.70
Purchase #5	$90.28	10.601%	$99.8506	$99.85	$99.85	$99.90
Purchase #6	$181.86	7.208%	$194.9685	$194.97	$194.95	$195.00
Purchase #7	$91.75	7.614%	$98.7358	$98.74	$98.75	$98.70
7 purchase totals =	$940.55		$1,016.5439	$1,016.55	$1,016.50	$1,016.60