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	$244.73	7.708%	$263.5938	$263.59	$263.60	$263.60
Purchase #2	$46.55	8.109%	$50.3247	$50.32	$50.30	$50.30
Purchase #3	$35.81	7.753%	$38.5863	$38.59	$38.60	$38.60
Purchase #4	$7.38	6.824%	$7.8836	$7.88	$7.90	$7.90
Purchase #5	$209.40	4.377%	$218.5654	$218.57	$218.55	$218.60
Purchase #6	$168.94	10.608%	$186.8612	$186.86	$186.85	$186.90
Purchase #7	$220.86	12.454%	$248.3659	$248.37	$248.35	$248.40
7 purchase totals =	$933.67		$1,014.1809	$1,014.18	$1,014.15	$1,014.30