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	$133.56	5.774%	$141.2718	$141.27	$141.25	$141.30
Purchase #2	$24.66	4.353%	$25.7334	$25.73	$25.75	$25.70
Purchase #3	$244.34	8.238%	$264.4687	$264.47	$264.45	$264.50
Purchase #4	$191.55	13.867%	$218.1122	$218.11	$218.10	$218.10
Purchase #5	$224.59	8.744%	$244.2281	$244.23	$244.25	$244.20
Purchase #6	$67.31	7.767%	$72.538	$72.54	$72.55	$72.50
Purchase #7	$217.91	9.645%	$238.9274	$238.93	$238.95	$238.90
7 purchase totals =	$1,103.92		$1,205.2796	$1,205.28	$1,205.30	$1,205.20