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	$177.50	3.849%	$184.332	$184.33	$184.35	$184.30
Purchase #2	$19.29	4.522%	$20.1623	$20.16	$20.15	$20.20
Purchase #3	$56.79	4.137%	$59.1394	$59.14	$59.15	$59.10
Purchase #4	$141.91	6.743%	$151.479	$151.48	$151.50	$151.50
Purchase #5	$196.29	7.816%	$211.632	$211.63	$211.65	$211.60
Purchase #6	$74.62	9.295%	$81.5559	$81.56	$81.55	$81.60
Purchase #7	$224.44	7.168%	$240.5279	$240.53	$240.55	$240.50
7 purchase totals =	$890.84		$948.8285	$948.83	$948.90	$948.80