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	$152.63	10.827%	$169.1553	$169.16	$169.15	$169.20
Purchase #2	$53.61	6.827%	$57.27	$57.27	$57.25	$57.30
Purchase #3	$98.69	5.826%	$104.4397	$104.44	$104.45	$104.40
Purchase #4	$123.75	5.272%	$130.2741	$130.27	$130.25	$130.30
Purchase #5	$88.85	11.728%	$99.2703	$99.27	$99.25	$99.30
Purchase #6	$185.97	5.869%	$196.8846	$196.88	$196.90	$196.90
Purchase #7	$176.52	4.784%	$184.9647	$184.96	$184.95	$185.00
7 purchase totals =	$880.02		$942.2587	$942.25	$942.20	$942.40