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	$148.80	12.414%	$167.272	$167.27	$167.25	$167.30
Purchase #2	$68.97	13.584%	$78.3389	$78.34	$78.35	$78.30
Purchase #3	$47.36	10.132%	$52.1585	$52.16	$52.15	$52.20
Purchase #4	$212.78	11.164%	$236.5348	$236.53	$236.55	$236.50
Purchase #5	$241.29	3.802%	$250.4638	$250.46	$250.45	$250.50
Purchase #6	$186.43	12.613%	$209.9444	$209.94	$209.95	$209.90
Purchase #7	$243.33	10.363%	$268.5463	$268.55	$268.55	$268.50
7 purchase totals =	$1,148.96		$1,263.2587	$1,263.25	$1,263.25	$1,263.20