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	$43.91	6.512%	$46.7694	$46.77	$46.75	$46.80
Purchase #2	$175.91	3.578%	$182.2041	$182.20	$182.20	$182.20
Purchase #3	$198.69	11.523%	$221.585	$221.59	$221.60	$221.60
Purchase #4	$211.35	6.404%	$224.8849	$224.88	$224.90	$224.90
Purchase #5	$161.94	12.490%	$182.1663	$182.17	$182.15	$182.20
Purchase #6	$142.89	6.476%	$152.1436	$152.14	$152.15	$152.10
Purchase #7	$74.93	10.120%	$82.5129	$82.51	$82.50	$82.50
7 purchase totals =	$1,009.62		$1,092.2662	$1,092.26	$1,092.25	$1,092.30