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	$46.66	5.266%	$49.1171	$49.12	$49.10	$49.10
Purchase #2	$179.92	9.208%	$196.487	$196.49	$196.50	$196.50
Purchase #3	$211.95	6.565%	$225.8645	$225.86	$225.85	$225.90
Purchase #4	$211.82	9.561%	$232.0721	$232.07	$232.05	$232.10
Purchase #5	$187.47	7.247%	$201.056	$201.06	$201.05	$201.10
Purchase #6	$140.31	9.651%	$153.8513	$153.85	$153.85	$153.90
Purchase #7	$32.59	13.640%	$37.0353	$37.04	$37.05	$37.00
7 purchase totals =	$1,010.72		$1,095.4833	$1,095.49	$1,095.45	$1,095.60