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	$183.40	6.316%	$194.9835	$194.98	$195.00	$195.00
Purchase #2	$155.67	4.657%	$162.9196	$162.92	$162.90	$162.90
Purchase #3	$232.26	3.529%	$240.4565	$240.46	$240.45	$240.50
Purchase #4	$38.78	9.613%	$42.5079	$42.51	$42.50	$42.50
Purchase #5	$78.26	10.813%	$86.7223	$86.72	$86.70	$86.70
Purchase #6	$249.89	7.615%	$268.9191	$268.92	$268.90	$268.90
Purchase #7	$110.61	3.786%	$114.7977	$114.80	$114.80	$114.80
7 purchase totals =	$1,048.87		$1,111.3066	$1,111.31	$1,111.25	$1,111.30