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	$191.34	6.620%	$204.0067	$204.01	$204.00	$204.00
Purchase #2	$85.70	6.728%	$91.4659	$91.47	$91.45	$91.50
Purchase #3	$241.45	9.707%	$264.8876	$264.89	$264.90	$264.90
Purchase #4	$42.86	6.678%	$45.7222	$45.72	$45.70	$45.70
Purchase #5	$235.79	7.410%	$253.262	$253.26	$253.25	$253.30
Purchase #6	$65.81	6.800%	$70.2851	$70.29	$70.30	$70.30
Purchase #7	$231.95	11.717%	$259.1276	$259.13	$259.15	$259.10
7 purchase totals =	$1,094.90		$1,188.7571	$1,188.77	$1,188.75	$1,188.80