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	$88.91	7.113%	$95.2342	$95.23	$95.25	$95.20
Purchase #2	$18.47	12.860%	$20.8452	$20.85	$20.85	$20.80
Purchase #3	$208.75	12.289%	$234.4033	$234.40	$234.40	$234.40
Purchase #4	$152.90	9.470%	$167.3796	$167.38	$167.40	$167.40
Purchase #5	$212.44	10.102%	$233.9007	$233.90	$233.90	$233.90
Purchase #6	$203.68	12.105%	$228.3355	$228.34	$228.35	$228.30
Purchase #7	$217.68	11.290%	$242.2561	$242.26	$242.25	$242.30
7 purchase totals =	$1,102.83		$1,222.3546	$1,222.36	$1,222.40	$1,222.30