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	$112.56	11.272%	$125.2478	$125.25	$125.25	$125.20
Purchase #2	$212.76	11.736%	$237.7295	$237.73	$237.75	$237.70
Purchase #3	$73.67	11.626%	$82.2349	$82.23	$82.25	$82.20
Purchase #4	$32.76	13.865%	$37.3022	$37.30	$37.30	$37.30
Purchase #5	$188.92	12.790%	$213.0829	$213.08	$213.10	$213.10
Purchase #6	$88.79	13.491%	$100.7687	$100.77	$100.75	$100.80
Purchase #7	$103.77	8.320%	$112.4037	$112.40	$112.40	$112.40
7 purchase totals =	$813.23		$908.7697	$908.76	$908.80	$908.70