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	$175.80	5.735%	$185.8821	$185.88	$185.90	$185.90
Purchase #2	$64.77	11.158%	$71.997	$72.00	$72.00	$72.00
Purchase #3	$199.76	11.468%	$222.6685	$222.67	$222.65	$222.70
Purchase #4	$206.80	13.596%	$234.9165	$234.92	$234.90	$234.90
Purchase #5	$53.78	8.127%	$58.1507	$58.15	$58.15	$58.20
Purchase #6	$190.30	5.380%	$200.5381	$200.54	$200.55	$200.50
Purchase #7	$25.83	5.372%	$27.2176	$27.22	$27.20	$27.20
7 purchase totals =	$917.04		$1,001.3705	$1,001.38	$1,001.35	$1,001.40