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	$171.77	13.498%	$194.9555	$194.96	$194.95	$195.00
Purchase #2	$41.39	3.708%	$42.9247	$42.92	$42.90	$42.90
Purchase #3	$209.38	11.625%	$233.7204	$233.72	$233.70	$233.70
Purchase #4	$173.56	11.625%	$193.7364	$193.74	$193.75	$193.70
Purchase #5	$112.26	4.758%	$117.6013	$117.60	$117.60	$117.60
Purchase #6	$88.52	11.139%	$98.3802	$98.38	$98.40	$98.40
Purchase #7	$159.97	4.705%	$167.4966	$167.50	$167.50	$167.50
7 purchase totals =	$956.85		$1,048.8151	$1,048.82	$1,048.80	$1,048.80