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	$148.28	10.744%	$164.2112	$164.21	$164.20	$164.20
Purchase #2	$41.85	7.795%	$45.1122	$45.11	$45.10	$45.10
Purchase #3	$171.83	7.835%	$185.2929	$185.29	$185.30	$185.30
Purchase #4	$242.54	13.757%	$275.9062	$275.91	$275.90	$275.90
Purchase #5	$89.87	12.780%	$101.3554	$101.36	$101.35	$101.40
Purchase #6	$240.74	9.468%	$263.5333	$263.53	$263.55	$263.50
Purchase #7	$11.94	4.746%	$12.5067	$12.51	$12.50	$12.50
7 purchase totals =	$947.05		$1,047.9179	$1,047.92	$1,047.90	$1,047.90